Patanjali Yoga Sutra — बलेषु हस्तिबलादीनि ॥3.25॥
Through saṃyama on strength, a yogi can become as strong as an elephant, so on and so forth.
In the olden days, the wrestlers used to practice wrestling and other body-strengthening workouts before an idol or a picture of Lord Hanumān, the embodiment of strength and valor. Lord Hanumān was their iṣṭadaiva. Great warriors like Bhīmasena, Arjuna, etc were meditating on powerful deities like Hanumān, Lord śiva, Vīrabhadra, etc, before facing the opponents in the arena. Śrīrāma meditates on sūrya bhagavān, one of the mightiest of the Gods, by reciting āditya Hṛdayam, before facing rāvaṇa, the great demon of Laṅka. We see many such instances. Such meditation was giving them great confidence coupled with unparalleled sātvik mighty potency. Before attending examination our students worship the Goddess of knowledge, Saraswati Mātā. On the other hand, strengthening oneself (either physically or mentally) without mind culture could lead to Tāmasik acts. Though repetition, it is worth mentioning, ‘We are not different from what we do, what we think, what we hear, what we read, what we eat, what we say, whom we meet as our friends, etc. We are the embodiment of what our sādhana is.’
A rajakaḥ (washerman) approached śrī rāmakr̥ṣṇa Paramahaṁsa with a request to teach meditation. The latter asked, on which object the former would like to meditate upon. The former said, ‘I know my he-buffalo very well and I can meditate upon that form.’ śrī rāmakr̥ṣṇa agreed and sent him to a lonely room in the backyard of his house. After a prolonged meditation, śrī rāmakr̥ṣṇa called him to come out of the room. He exclaimed, ‘How can I come out, my horns are very broad and the exit is not wide enough for me to come out!’
Lord gives an interesting message in Bhagavad Gītā:
यो यो यां यां तनुं भक्त: श्रद्धयार्चितुमिच्छति। तस्य तस्याचलं श्रद्धां तामेव विदधाम्यहम् ॥७.२१॥
स तया श्रद्धया युक्तस्तस्याराधनमीहते। लभते च ततः कामान्मयैव विहितान्हि तान्॥७.२२॥
Whatever celestial form a devotee seeks to adore with utmost faith, it is I who make his devotion steadfast and steady in that particular deity. When intensely absorbed in that devotion the devotee gets the fruits of his wishful worship. Verily these fulfillments are granted by Me alone.